BlockFi seems to be the platform with more reputation. But since the recent news we're getting with back to back regulatory issues, I wouldn't recommend it or any staking platform in general (I wasn't really a fan of any of em in the first place).
Personally, I'm happy with just holding my bitcoin on my non-custodial wallet and simply just waiting for the price to appreciate.
I think Blockfi got some guys criticizing it because it didn't want to show proof of reserves, plus had no insurance (this was sometime last year though don't know if they got it today). It is the preferred platform of big media influencers though.
Nexo on the other hand seems to have Bitgo/Lloyds insurance, but I think it was really low like $100 million, which obviously seems to me that if it goes down, people only get back a fraction of their deposits:)
I've been keeping an eye on Nexo ever since
this thread started, and I actually went ahead with Nexo (you might remember it, as you responded here).
Nexo still haven't won me over BUT they do seem the best of the worst (custodial being the bad thing here). They've increased their insurance, displayed all their licenses and apparently are working on a proof-of-reserves solution that any client can access in real time.
I will update the thread there shortly now that I'm reminded, there's been quite a bit going on with them since then to improve their offering (bigger insurance, more licenses, proof of reserves)